A variety of materials with abrasion-resistant surfaces is known from the prior art which are used as floor coverings or furniture surfaces. In this context laminate floors are particularly widespread which are relatively inexpensive and have excellent abrasion-resistant surfaces. Such laminate floors are usually based on a support plate or a support layer made of MDF- or HDF-material, on top of which one or more resin-impregnated paper layers are applied. The used resins are typically amino resins which are cured by pressing under the influence of heat and pressure. The resins or the impregnated papers are also often provided with abrasion-resistant particles, to increase the abrasion-resistance of the surface. Therefore, abrasion-resistant particles can be added to the resin prior to impregnation of the paper in a particle size of typically 40 to 140 μm and/or the particles are added to the still undried paper after the impregnation, thus before it is cured.
In EP O 732 449 A1, hereto, a special resin mixture is proposed which consists of a mixture of water, melamine resin, alpha cellulose in a predetermined fiber length and amount and corundum powder with a particle size of about 20 to 50 μm. Thereby, the corundum powder in the mixture should be finely dispersed and should be fixed to the fibers of alpha cellulose. Hereby, the mineral remains homogeneous in dispersion and the cellulose fibers ensure that the resin contained in the mixture no longer penetrates into the decorative sheet, but rather remains mainly on the surface and forms a relatively thick resin layer.
EP 2 288 500 B1 also discloses a laminate and a method for its manufacturing. The underlying problem of this document is that the added abrasion-resistant particles induce a loss of gloss and transparency of the laminate on the one hand and the press plates used for the manufacturing of the laminate damage or wear on the other hand. As a solution, this publication proposes to impregnate a paper with an aminoplast resin and to dry in a first step. Then, a dispersion consisting of surface-modified silica nanoparticles and a dispersing agent should be applied on this already impregnated paper. Thereby, the dispersing agent should consist of for example water or polar solvents. The usage of the surface-modified silica nanoparticles should lead to improved compatibility of the nanoparticles with the aminoplast resin matrix, resulting in a homogeneous distribution of the nanoparticles in the resin matrix and a uniform distribution upon the surface of the already impregnated paper. Thereby, a significantly improved resistance of the so generated surface should result from the improved embedding of the nanoparticles. Such a generated laminate should be suitable for the use as floor covering, tabletop or generally in the manufacturing of furniture for the manufacturing of other furniture. This way, micro scratch-resistant surfaces can be generated, however, the procedure is very expensive.
The manufacturing and application of powder materials on the glass basis is known from EP 2 397 448 A1 which are particularly suitable for use in melamine resins and the like for coating floor panels. For example, finely grated borosilicate glass can be processed well with melamine resin, whereas finely ground sodium lime glass as an additive to the melamine resin is less suitable, since hereby no homogenous, continuous film can be formed. In this document, the problem is therefore already mentioned that not every additive is suitable for the processing with a melamine resin or the like, but on the contrary, it is extremely difficult to find suitable materials.
An amino resin is known from WO 2007/048731 A1 which is provided with anorganic nanoparticles, such as for example silicon oxide particles in size from 2 to 500 nm.
Thereby, the nanoparticles serve to make surfaces, which are provided with the amino resin, more abrasion-resistant.
Decorative laminates are described in EP 0 136 577 A2 which comprise resin-impregnated decorative papers which are applied on a support plate of e.g. fiber plates or the like. Nanoparticles are added in a size of 5 to 100 nm to this to increase the scratch-resistance of the surface.
While the methods known from the prior art can indeed lead to satisfactory abrasion values, so, the generated surfaces anyway comprise an unsatisfactory abrasion-resistance (also referred to as scratch-resistance or micro scratch-resistance) and/or the manufacturing of the surfaces is complex or expensive. The person skilled in the art understands the abrasion-resistance or micro scratch-resistance as the resistance of surfaces against scratches with very low depth, which often can already be generated by cleaning operations with soft materials per se. Such micro-scratches typically have a depth of no more than about 6 μm and, are in particular an optical impairment of the surfaces and are not so much an impairment of the functional properties. Therefore, a surface can comprise a good abrasion-resistance—and thus withstand the typical stresses well, leading to deep scratches (also in the order of fractions of millimeters)—and can still be sensitive to micro-scratches. In other words, a surface, which is optimized on good abrasion-resistance, is regularly not necessarily also in view of scratch-resistance optimal.
There have been repeated attempts for nanoparticle modifications for amino resins which have not been established yet for reasons of cost and for reasons of processing difficulties. In contrast to the amino resins, nanoparticle modifications can be made much easier in acrylate resins which lead to an improved scratch-resistance. It meets today to the prior art to achieve very high micro scratch-resistance for acrylate-coated surfaces. As an example, the X-add® KR.9006 of the Nano-X GmbH is mentioned. If the amino resin surfaces should be competitive against the acrylate resin surfaces in the future, economically and technically sustainable developments are required. Therefore, the objective of the present invention is to provide a special dispersion for manufacturing of a resin-impregnated paper with which the abrasion-resistant particles can be suitably supplied, so that herewith generated surfaces have an improved micro scratch-resistance. Thereby, it is in particular an objective of the invention to provide a dispersion which can readily be processed together with the resins usually used and in which very fine abrasion-resistant particles with an average size of only about 18 to 1 μm (according to the FEPA-Standard 42-2 (2006) for the products F400 to F2000) can be very homogeneously dispersed. It is also an objective of the invention to provide a method for the manufacturing of laminate materials which is suitable for the manufacturing of laminate floors, furniture surfaces etc. as well as such a product, with which relatively fine corundum particles are used and which comprises an excellent scratch-resistance.
These objectives are achieved with a dispersion according to claim 1, a method for manufacturing of a laminate material according to claim 7 as well as a laminate material according to claim 12.